I am
studying the effect of “impurity patterning” on the evolution of Si surfaces
during epitaxial growth.Within the
regime of temperature and incident flux where incident atoms can diffuse over
distances at least as large as the average terrace width before colliding with
other atoms, growth is primarily by step-flow.Certain impurities retard, or even halt the motion of steps (step
pinning) across the surface.The goal of
my research is to investigate the patterns which evolve due to the interference
of the impurity particles with step flow, as the growth parameters and the
configuration of impurities are varied.

I’ve been using photolithography
and electron beam evaporation of SiC, to create dots
of different sizes and spacing on Si(111) surfaces,
followed by Si epitaxial growth.Finally
I use using tapping mode AFM (Atomic Force Microscopy, digital instruments) to
examine the resulting topography.

A second
aspect of my work concerns patterning the surface lithographically to form
arrays of pits.The samples are prepared
via photolithography and RIE (Reactive Ion Etching).Pits act as sources of steps, and can locally
accelerate the motion of steps locally during growth, or sublimation.

My research is supported by the National Science Foundation
under a Materials Research Science and EngineeringCenter, and by the Laboratory for Physical Sciences.